b'Engineer Innovation | Electronics & SemiconductorThermalStructuralT3STer Master: ZthResistance Analysis 35QFN TTV_0.36A_1mA_Rthja - ch. 1 From Measurement3025Zth [K/M]2015 28.741050ModelModel1e-61e-40.01110010000CTM Calibration Time [S]Figure 2: Novel workflow involving test and simulation Figure 3: Z ththermal impedance of a QFN packageStructure Functions cannot be extracted. Ideally, 1e+06 1e+06 information on the internal structure 100000 100000 needs to be known to optimize theThermal Capacitance (Ws/K) Capacitance / Resistance (W^2s/K^2)10000 TIM Lid Pad Environment 10000 design.1000 1000100 Novel workflow100A new workflow is now being used at 10 10 ASE (Figure 2). This involves the use the 1 1 Simcenter T3STER transient thermal 0.1 0.1 tester hardware and the auto-calibration 0.01 0.01 function in Simcenter Flotherm.0.001 0.0010.0001 The IC Package is tested using the 0.0001Simcenter T3STER initially. From the 1e-05 1e-0500. measured junction temperature, thisThermal Resistance (K/W) yields the thermal impedance as a function of time for the package, as Figure 4a: Structure function curve for a HFCBGA package shown in Figure 3.Information on the thermal resistances PCB and thermal capacitances along the heat flow path for the measured R R package can be obtained by Lid Die mathematically processing the thermal impedance curve, which results in a R structure function curve. The structure R Pad Cold Plate TIM function curve gives an insight into the internal structure of the package (Figure 4a and 4b).Figure 4b: Cross-sectional view of a HFCBGA PackageBeing able to quantify the resistances and capacitances of the individual optimization studies on the IC packageinternal structural elements of the geometry prior to releasing the product.packages is of added value to ASEs To that end, traditional testcustomers. They are able to identify methodology is not able to help withthermal bottlenecks easily and ASE this requirement. With the simplewould be able to optimize the internal Still-Air, Ring Cold plate or Top Coldstructures of the design, to reduce the plate test harnesses, only a few pointjunction temperature.temperatures are obtained on the outside of the packages, butASE use structure function graphs to information about the actual structurecalibrate the detailed Simcenter 68'